Put the vinegar in a bowl and add the shallots. Let stand for 5 minutes or so. Add the capers, cornichons, parsley, chervil, chives, salt, and pepper and stir together. Stir in ½ cup of olive oil and taste, adjusting for salt and pepper as desired. Add more olive oil if the sauce tastes too sharp. The sauce can be covered and stored in the refrigerator for up to a week.